The invention is related to cleaning systems, in particular one which is suited for cleaning heavily soiled surfaces, particularly tanks, vats and other containers.
Many industrial containers, including truck tankers, railroad tank cars and stationary tanks and vats, must be cleaned, usually after the tank is empty, to remove any material or contaminants left on the container surfaces. To do so, the surfaces to be cleaned are usually sprayed with a high pressure cleaning liquid to dislodge the contaminants, both liquid and solid, from the surfaces. Because the impact of the high pressure spray is diffused if there is a liquid layer within the tank, it is desirable to keep the amount of cleaning liquid which gathers at the bottom of the tank to a minimum. This is preferably done by constantly removing the cleaning liquid and dislodged contaminants.
The cleaning liquid and dislodged contaminants may both be liquid. However, the mixture is often a sludge containing liquids, viscous materials and solids. Some type of containers, such as oil tankers, pose special problems for tank cleaning apparatus. Oil pumped out of the ground contains rocks, sand and gravel. In addition to this naturally occurring foreign matter, a great number of rags find their way into oil holding compartments of oil tankers. The presence of contaminants which both float and sink create additional problems during cleaning operations. What has been missing from the prior art is a mobile cleaning unit capable of efficiently removing and processing multi-component sludge.